For the first time, the self-consistent spectrophotometric acidity scale of neutral Bronsted acids in acetonitrile (AN) spanning 24 orders of magnitude of acidities is reported. The scale ranges from pKa 3.7 to 28.1 in AN. The scale includes 93 acids that are interconnected by 203 relative acidity measurements (ΔpKa measurements) and contains compounds with gradually changing acidities, including representatives from all of the conventional families of OH (alcohols, phenols, carboxylic acids, sulfonic acids), NH (anilines, diphenylamines, disulfonimides), and CH acids (fluorenes, diphenylacetonitriles, phenylmalononitriles). The CH acids were particularly useful in constructing the scale because they do not undergo homo- or heteroconjugation processes and their acidities are rather insensitive to traces of water in the medium. The scale has been fully cross-validated:  the relative acidity of any two acids on the scale can be found by combining at least two independent sets of ΔpKa measurements. The consi...

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A Comprehensive Self-Consistent Spectrophotometric Acidity Scale of Neutral Brønsted Acids in Acetonitrile

Enzymatic membrane bioreactors and their applications

Hindered tertiary nitriles can be hydrolyzed under neutral and mild conditions to the corresponding amides using platinum(II) catalysts with dimethylphosphine oxide or other secondary phosphine oxides (SPOs, phosphinous acids) as ligands. We have found that this procedure also works well for nitriles with acid- or base-sensitive groups, which is unprecedented in terms of yield and selectivity. The catalyst loading can be as low as 0.5 mol %. Amides are isolated as the only product in high yield, and no further hydrolysis to the corresponding acids takes place. Reactions are carried out at 80 °C but take place even at room temperature. When enantiopure secondary phosphine oxide ligands are used in the hydrolysis of racemic nitriles, no kinetic resolution is observed, presumably due to racemization of the ligand during the reaction.

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Platinum-Catalyzed Selective Hydration of Hindered Nitriles and Nitriles with Acid- or Base-Sensitive Groups

Studies in Molecular Replication

Publisher Summary This chapter explains that many developments have taken place in the applications of gas–liquid chromatography to carbohydrates. The chapter discusses a classical paper on the application of trimethylsilyl derivatives of carbohydrates in gas–liquid chromatography. The discovery that these derivatives are readily formed and that they are volatile revolutionized the separation and analysis of carbohydrate mixtures. The chapter reviews the determination of carbohydrates in biological materials by gas–liquid chromatography and the use of this method in the analysis of plant materials. In examining the structure of a polysaccharide, it is convenient to consider the methods involved under the three main headings: (1) quantitative analysis, ( 2 ) methylation, and (3) periodate oxidation. Each of these aspects of polysaccharide chemistry may be aided by the application of gas–liquid chromatography, either qualitative or quantitative, or both. Thus, separations impossible by other techniques may often be achieved, and analytical data obtained in a fraction of the time demanded by other methods.

Peter R. Rony

Papers

Polyfunctional catalysis. III. Tautomeric catalysis

Hollow fiber enzyme reactors.

Polyfunctional catalysis. I. Activation parameters for the mutarotation of tetramethyl-D-glucose in benzene

Polyfunctional catalysis. II. General base catalysis of the mutarotation of tetramethyl-D-gluose in benzene and methanol-benzene